Difference between lean concrete and PCC Concrete

Lean Concrete

The main difference between lean and PCC Concrete is, In lean concrete, the cement content is less compared to the water content in the concrete.

It can also say that the ratio of cement content to water and coarse aggregate content is low compared to plain cement concrete.

The higher the Aggregate/cement ratio, the leaner the concrete. In lean concrete, less quantity of paste is available for providing lubrication, per unit surface of aggregate and hence the mobility of aggregate is restricted 

The below picture shows the casting of lean concrete,

 

Difference between lean and pcc concrete.

Example:-

M5 GRADE OF CONCRETE → 1:5;10 (CEMENT:SAND:AGGREGATES) {5mpa}

M7.5 GRADE OF CONCRETE→1:4:8 (CEMENT:SAND:AGGREGATES) {7.5mpa}

Main purpose of lean concrete:-

  1. Main function of the lean concrete is to provide the uniform surface to the foundation concrete and to prevent the direct contact of foundation concrete from the soil.
  2. Lean concrete is used under the foundations.
  3. It is good for providing a flat bottom in uneven or dirt terrain.
  4. Lean concrete has a lower level of cement in it, which is why it’s mostly used for fillings or under the foundations, to keep it protected from the soil.
  5. Lean concrete is used to provide a level surface , where main foundation (raft, isolated or any other type) can be placed.
  6. Another purpose is protection of main foundation from soil below, as moisture or other chemicals in soil like sulphates may attack concrete and can weaken it.

If you need a quality foundation and the entire structure as a whole, then use lean concrete.Next we are going to tell about plain cement concrete in our difference between lean concrete and pcc concrete article.

Plain Cement Concrete

The mixture of cement, fine aggregate (sand) and coarse aggregate are called plain cement concrete (PCC).Now a days, PCC is widely used for construction purpose.

Example:-

M10 GRADE OF CONCRETE → 1:3:6 (CEMENT:SAND:AGGREGATES) {10mpa}

M15 GRADE OF CONCRETE→1:2:4 (CEMENT:SAND:AGGREGATES) {15mpa}

Main Purpose of PCC:-

  1. It is used as a protective layer for the RCC above so that water from the RCC is not absorbed by the earth below.
  2. Moisture available in soil should not absorbed by R.C.C footings which causes corrosion of reinforcement.
  3. Provides a base for the concrete and also helps workers to set out the structure above in an easier way. It provides a flat base for upcoming foundation rather than the undulated base.
  4. The effective depth of RCC member is achieved as the form-works can be easily and sturdily fixed.
  5. As the Grade of concrete of PCC and Foundation is different it also provides the material difference for ground bactrial effect on foundation.
  6. Act as a cover to reinforced cement concrete i.e. resist corrosion of steel bars in footings.
  7. Sometimes it can decrease the stresses to the soil.

These are the difference between lean concrete and pcc concrete.

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